Arthroscopic devices and methods

ABSTRACT

An elongated shaft assembly includes a rotatable inner cutting sleeve and a non-rotating outer sleeve. A window of the inner cutting sleeve is selectively rotatable within an opening of the non-rotating outer sleeve to cut tissue with a sharpened cutting blade when rotated in a first rotational direction and to cut tissue with an electrode when rotated in a second rotational direction.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.15/599,372 (Attorney Docket No. 41879-720.401), filed May 18, 2017,which is a divisional of U.S. patent application Ser. No. 15/096,546(Attorney Docket No. 41879-720.201), filed Apr. 12, 2016, now U.S. Pat.No. 9,681,913, which claims the benefit of provisional application62/150,758 (Attorney Docket No. 41879-720.101), filed on Apr. 21, 2015,the full disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

This invention relates to arthroscopic tissue cutting and removaldevices by which anatomical tissues may be cut and removed from a jointor other site. More specifically, this invention relates to instrumentsconfigured for cutting and removing soft tissue and hard tissue withboth mechanical cutting means and electrosurgical cutting means.

In several surgical procedures including subacromial decompression,anterior cruciate ligament reconstruction involving notchplasty, andarthroscopic resection of the acromioclavicular joint, there is a needfor cutting and removal of soft tissues as well as bone. Currently,physicians use two or more arthroscopic devices to perform such aprocedure. For example, a mechanical shaver may used to cut soft tissuewhile a high speed bone burr may be used to remove bone. In addition,one or more RF probes may also be used to cut certain types of tissue,to contour tissue surfaces, or to coagulate and seal tissue.

A typical arthroscopic shaver or burr comprises a metal cutting membercarried at the distal end of a metal sleeve that rotates within anopen-ended metal shaft. A suction pathway for removal of bone fragmentsor other tissues is provided through a window proximal to the metalcutting member that communicates with a lumen in the sleeve.

When metal shavers and burrs “wear” during a procedure, which can occurvery rapidly when cutting bone, the wear can be accompanied by loss ofmicro-particles from fracture and particle release which occurs alongwith dulling due to metal deformation. In such surgical applications,even very small amounts of such foreign particles that are not recoveredfrom a treatment site can lead to detrimental effects on the patienthealth, with inflammation being typical. In some cases, the foreignparticles can result in joint failure due to osteolysis, a term used todefine inflammation due to presence of such foreign particles. A recentarticle describing such foreign particle induced inflammation isPedowitz, et al. (2013) Arthroscopic surgical tools: “A source of metalparticles and possible joint damage”, Arthroscopy—The Journal ofArthroscopic and Related Surgery, 29(9), 1559-1565. In addition tocausing inflammation, the presence of metal particles in a joint orother treatment site can cause serious problems for future MRIs.Typically, the MRI images will be blurred by agitation of the metalparticles caused by the magnetic field used in the imaging, makingassessments of the treatment difficult.

Another problem with the currently available arthroscopic shavers isthat mechanical cutting does not work well with some types of tissue. RFplasma-based electrosurgical cutting would be preferred, but reliable RFplasma shavers have not been developed.

Therefore, the need exists for arthroscopic shavers that can operate tocut and remove both soft tissue and bone tissue and further to removebone tissue without the release of fractured particles andmicro-particles into the treatment site. Further, there is a need forarthroscopic shavers that can use RF plasma for tissue resection. Atleast some of these objectives will be met by the inventions describedbelow.

2. Description of the Background Art

Pedowitz, et al. (2013) Arthroscopic surgical tools: “A source of metalparticles and possible joint damage”, Arthroscopy—The Journal ofArthroscopic and Related Surgery, 29(9), 1559-1565 has been discussedabove. Co-pending, commonly assigned U.S. patent application No.14/960,084 (Attorney Docket No. 41879-712.201), filed on Dec. 4, 2015,and Ser. No. 14/977,256 (Attorney Docket No. 41879-712.202), filed onDec. 21, 2015, the full disclosures of which are incorporated herein byreference, have disclosures related to the present application. See alsoU.S. Pat. Nos. 6,149,620 and 7,678,069.

SUMMARY OF THE INVENTION

In a first aspect of the present invention, a method for treating tissuecomprises engaging a working end of a shaft assembly against a tissueinterface. The working end includes an outer sleeve having a distalopening and an inner sleeve having a cutting window. A portion of thetissue interface is contacted by the inner sleeve's cutting window whenexposed in the opening in the outer sleeve. The inner sleeve can berotated in a first rotational direction relative to the outer sleeve tocut tissue engaged by a cutting edge on one side of the cutting window,typically by shearing with an opposed edge on the outer sleeve opening.The inner sleeve can be rotated in a first rotational direction relativeto the outer sleeve to cut tissue extending through said windows as acutting edge on one side of the inner cutting window passes through thetissue, typically by shearing with an opposed cutting edge on the distalopening. The inner sleeve can also be rotated in a second rotationaldirection opposite to the first rotational direction to cut tissue withan energized electrode disposed on or near (proximate) an opposite sideof the cutting window of the inner sleeve.

In particular embodiments of the method of the present invention, theinner sleeve may be rotated in the first rotational direction to shearbone and other hard tissues and may be rotated in the second rotationalto advance an energized electrode to cut soft tissue. Exemplary hardtissues include bone and the like, and exemplary soft tissues includemuscle, nerve tissue, cartilage, meniscus, connective tissue, tendons,and ligaments, and the like. The tissue interface may be submerged in aliquid or a liquid may be directed at the tissue interface through achannel in the shaft assembly while engaging the working end androtating the inner sleeve. Additionally, a negative pressure may bedrawn through a passageway in the shaft assembly to remove cut tissueand other debris through the passageway.

In further embodiments of the methods of the present invention, a motorassembly may be detachably secured to the shaft assembly. The motor isconfigured to selectively rotate the inner sleeve or shaft in the firstand second rotational directions. A radiofrequency (RF) power supply mayalso be detachably secured to the shaft assembly. The RF power supply isconfigured to selectively energize the electrode. A controller may beoperatively attached to the motor and/or to the RF power supply. Thecontroller may be configured to control the RF power supply toselectively deliver RF cutting current to the electrode when the motorrotates the inner sleeve in a cutting direction and to selectively notdeliver cutting current to the electrode when the motor is not rotatingthe inner sleeve in the cutting direction.

Usually, a cutting current is delivered to the electrode only while theelectrode is being rotated in a cutting direction. In a specificprotocol, the cutting current is delivered to the electrode only duringa selected arc of rotation of the inner sleeve. In an alternateprotocol, the cutting current is delivered to the electrode during fullrotation of the inner sleeve.

In still other embodiments of the methods of the present invention, theinner sleeve may be stopped in a selected rotational position relativeto the outer sleeve to align the sleeve window of the inner sleeve withthe opening in the outer sleeve in a selected orientation. Thecontroller may be configured to deliver a coagulating current from theRF power supply to the electrode while the inner sleeve is stationaryfor coagulating tissue.

In a second aspect of the present invention, a surgical system comprisesan outer sleeve having a longitudinal axis and an opening in a distalregion thereof. An inner sleeve is rotationally disposed within saidouter sleeve, and the inner sleeve has a distal region, a proximalregion, and an interior passageway disposed therebetween. A cuttingwindow is formed in a wall of the distal region of the inner sleeve, anda cutting edge is disposed on or along one side of the cutting window ofthe inner sleeve. An electrode is disposed on an opposite side of thecutting window of the inner sleeve so that rotating the inner sleeve ina first rotational direction relative to the outer sleeve cuts tissuewith the cutting edge of the inner sleeve window and rotating the innersleeve in a second rotational direction opposite to the first rotationaldirection cuts tissue engaged by the energized electrode.

In particular embodiments, the surgical systems of the present inventionmay further comprise a motor configured to selectively rotate in theinner sleeve in the first and second rotational directions. Said systemsmay still further comprise a radiofrequency (RF) current sourceconfigured to be coupled to the electrode, and often a controlleroperatively coupled to the motor and to the RF source.

The controller may be configured to selectively operate in a first modein which the motor rotates the inner sleeve in the first rotationaldirection with the electrode not energized and in a second mode in whichthe motor rotates the inner sleeve in the second rotational directionwith the RF source delivering an RF cutting or ablation current to theelectrode to cut tissue. Optionally, the controller may be furtherconfigured to selectively operate in a third mode in which the innersleeve is stopped in a selected position and the RF source delivers acauterizing current to electrode which can be positioned in contact withtissue to coagulate targeted tissue. The controller may be furtherconfigured to selectively operate in a fourth mode in which the innersleeve is stopped in a selected position and the RF source delivers acutting or ablation current to the electrode which can be translatedover tissue for surface ablation or contouring.

In still further options, the controller may be configured toselectively operate in a fifth mode in which the motor rotationallyoscillates the inner sleeve relative to the outer sleeve in the firstand second rotational directions. Further optionally, the controller maybe configured to selectively operate in a sixth mode in which the motordrives the inner sleeve rotationally and contemporaneously drives (1)the inner sleeve axially relative to the outer sleeve or (2) an assemblyof the inner and outer sleeves axially relative to a handle.

In other embodiments, the surgical systems of the present invention mayinclude a hub or handle disposed at a proximal end of the shaftassembly. The motor may be detachably connected to the hub or handle,and a proximal portion of the shaft assembly may be configured to beconnected to an external fluid source to deliver a fluid through apassageway in the shaft assembly and release the fluid from a distalregion of the shaft assembly to a tissue interface. A proximal portionof the shaft assembly may be configured to be connected to an externalvacuum source to draw a vacuum through a passageway in the shaftassembly to aspirate fluid from a tissue interface at a distal region ofthe shaft assembly.

In still other embodiments, at least the cutting edge of the innersleeve comprises a ceramic. Often, the entire distal portion of theinner sleeve comprises the ceramic.

In other alternative embodiments, the controller may be configured tostop rotation of the inner sleeve in a selected rotational positionrelative to the outer sleeve. For example, the opening in the outersleeve and the window in the inner sleeve may be rotationally aligned inthe stopped position. Alternatively, the opening in the outer sleeve andthe window in the inner sleeve may be out of rotational alignment in thestopped position.

In a third aspect of the present invention, a tissue treatment devicecomprises a shaft assembly having an outer shaft and an inner shaftco-axially received in the outer shaft. A hub or handle may be attachedto a proximal end of the shaft assembly, and a motor may be attachableto the hub or handle. The motor may be configured to rotatably drive theinner sleeve relative to the outer sleeve, and a window and an openingmay be formed in distal portions of the inner and outer sleeves,respectively. The inner opening includes a cutting blade along oneaxially aligned edge and an electrode along a second axially alignededge.

In a fourth aspect of the present invention, an arthroscopic tissuetreatment device comprises a shaft assembly having an outer shaft and aninner shaft received in a passageway of the outer shaft. The first andsecond shafts each have an opening formed in a distal portion thereof,and a hub may be attached to a proximal end of the shaft assembly. Amotor may be attachable to the hub, and the motor is typicallyconfigured to rotatably drive the inner shaft in first and secondrotational directions relative to the outer shaft. A cutting blade maybe formed or otherwise disposed on one side of the opening of the innersleeve, and an electrode may be formed or otherwise disposed on anopposed side of the opening of the inner sleeve. A coupler may beprovided to couple the shaft assembly to a handle and couple the innersleeve to the motor carried by the handle.

In a fifth aspect of the present invention, a tissue cutting instrumentfor differentially cutting tissue comprises an elongate shaft having aworking end with a moveable cutting member. A motor drive and controllermoves the cutting member, and the controller may be configured to movethe cutting member in a first direction to mechanically cut tissue andin a second different direction to electrosurgically cut tissue.

In particular embodiments, the first and second directions of the tissuecutting instruments of the present invention are opposing rotationaldirections. The cutting member may mechanically cut tissue with a sharpedge and/or may electrosurgically cut tissue with a cutting electrode.The tissue cutting instruments may further comprise a negative pressuresource communicating with a passageway in the cutting member forremoving cut tissue from a treatment site. The tissue cutting instrumentmay still further comprise an RF source and controller operativelycoupled to the electrode. Additionally, the controller of the tissuecutting instrument may be configured to energize the electrode only whenthe cutting member moves in the second direction.

The present invention further provides a high-speed cutter that isfabricated of a ceramic material that has a window with a first sidehaving a sharp cutting edge for mechanical cutting and a second sidewith an electrode for RF plasma-based cutting. In one variation, theceramic cutter is molded with sharp cutting edges and is adapted to bemotor driven at speeds ranging from 3,000 rpm to 20,000 rpm. The ceramiccutting member is coupled to an elongate inner sleeve that is configuredto rotate within a metal, ceramic or composite outer sleeve. While thecutting assembly and ceramic cutting member of the invention have beendesigned for arthroscopic procedures, such devices can be fabricated invarious cross-sections and lengths and can be use in other proceduresfor cutting bone, cartilage and soft tissue such as in ENT procedures,spine and disc procedures and plastic surgeries.

In still other aspects, the present invention provides a medical devicethat includes an elongated sleeve having a longitudinal axis, a proximalend and a distal end. A cutting member extends distally from the distalend of the elongated sleeve, and has sharp cutting edges. The cuttinghead is formed from a wear-resistant ceramic material, and a motorcoupled to the proximal end of elongated sleeve rotates the cuttingmember. The cutter may be engaged against bone and rotated to cut bonetissue without leaving any foreign particles in the site.

As used herein, the phrase “tissue interface” means a surface or exposedinterior volume of a target tissue to be treated with the devices andmethods of the present invention. The tissue may be a hard tissue, suchas bone, or may be a soft tissue, such as muscle, nerve tissue,cartilage, meniscus, connective tissue, tendons, ligaments, and thelike. The tissue interface may be present on a natural surface of a bodystructure, such as bone, cartilage, meniscus, connective tissue,tendons, or ligaments, or may be a surgically exposed tissue surface,such as surgically opened solid tissue. In exemplary procedures, thetissue surfaces will be accessed by minimally invasive surgicalprocedures, such as arthroscopy, laparoscopy, thoracoscopy, and thelike.

As used herein, the phrase “a portion of the tissue interface,” means apiece, segment, section, fragment, or the like of tissue interface to becut or excised from the remaining volume of the tissue interface by theapparatus and methods of the present invention.

As used herein, the phrase “a portion of the tissue interface engaged bya/the cutting window,” means pressing or otherwise contacting a workingend of the tissue resection apparatus of the present invention againstthe tissue interface which will cut hard tissue as a burr or will cutsoft tissue by causing a portion of tissue from the tissue interface tobe received in the aperture or opening which is created in the workingend when the inner and outer cutting openings are at least partiallyrotationally aligned.

As used herein, the phrases “adapted to” and “configured to” perform afunction mean that the structure of the device, apparatus, or componentsthereof is such that the device, apparatus, or components willnecessarily be able to perform the specified function as performed bythe exemplary structures described in the specification herein.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the present invention will now be discussed withreference to the appended drawings. It should be appreciated that thedrawings depict only typical embodiments of the invention and aretherefore not to be considered limiting in scope

FIG. 1 is a perspective view of an arthroscopic cutting system accordingto one exemplary variation.

FIG. 2 is an enlarged perspective view of the working end of the cuttingdevice of FIG. 1 showing windows or openings formed in an outer shaftand an movable inner shaft.

FIG. 3A is a perspective view of the distal end of inner shaft of FIG. 2separated from the outer shaft.

FIG. 3B is a perspective view of the outer shaft of FIG. 2 separatedfrom the inner shaft.

FIG. 4A is a perspective view of the electrode separated from the innershaft of FIG. 4B.

FIG. 4B is a perspective view of the distal end of the inner shaft setto receive the electrode of FIG. 4A.

FIG. 5A is a perspective view of the working end of an inner sleeve ofanother variation of a shaver blade similar to that of FIG. 3A.

FIG. 5B is a perspective view of the working end of an outer sleeve thatcarries the inner sleeve of FIG. 5A.

FIG. 6 is a sectional view of the distal end of a ceramic cutting membertaken along line 6-6 of FIG. 5A showing a method securing an electrodeto a ceramic body.

DETAILED DESCRIPTION OF THE INVENTION

The systems and methods of the present invention are illustrated anddescribed herein by means of a surgical system that is adapted for usein performing arthroscopic procedures or other similar procedures, forexample to remove, cut, trim, remodel, reshape or modify soft and hardtissues in a patient's shoulder, knee, hip or other joint. The surgicalsystem 100 and cutting device or shaver assembly 102 (FIG. 1) isparticularly suitable for performing procedures in a patient's jointthat requires resection of soft tissue as well as the cutting ormodification of bone. The system and methods of the present inventionare not limited to arthroscopy, and can further be used in endoscopicand laparoscopic procedures as well as open surgeries and roboticsurgical procedures.

FIG. 1 illustrates one variation of a surgical system 100 andarthroscopic cutting device or shaver assembly 102 that is adapted tocut both hard and soft tissue and thereafter suction the tissue chipsand debris through a passageway in the device to a collection reservoir.In a typical system, the cutting device 102 can be used in associationwith an independent fluid management system known in the art whichprovides for fluid inflows into a working space and for fluid outflowsfrom the working space as well as pressure monitoring and control. Inanother variation described below, the surgical system 100 and cuttingdevice 102 can have an integrated fluid management system.

In FIG. 1, it can be seen that the cutting device 102 has a shaftportion 104 that extends about longitudinal axis 105 and has a proximalhub 106 that can be detachably coupled to a non-disposable handle orhand piece 108 that carries a motor drive 110. As can be understood fromFIGS. 1 and 2, the elongate shaft 104 comprises an outer tubular shaftor sleeve 125 and an inner tubular shaft or sleeve 128. The inner sleeve128 is rotatably disposed in a bore 130 of the outer sleeve 125. Theassembly of outer sleeve 125 and inner sleeve 128 can be of any suitableouter diameter, for example between 2 mm and 10 mm suited for typicalarthroscopic procedures, and often would be from 3 mm to 6 mm in outerdiameter.

The user can actuate a finger-operated actuator mechanism or afootswitch to cause the inner sleeve 128 to move or rotate withininterior passageway 130 of outer sleeve 125. In one variation shown inFIG. 1, the hand piece 108 has an actuator mechanism 131A for sendingactivation signals and de-activation signals to a controller 160 tooperate the motor drive 110. In a variation, the actuator mechanism canselectively activate the motor drive to rotate in either rotationaldirection relative to axis 105, or the actuator mechanism 131A can beoperated to oscillate the inner sleeve a selected number of rotations ina first direction and then a selected number of rotations in theopposing direction. As will be described below, the system 100 also mayhave a footswitch 131B (or hand switch) for actuating an RF energydelivery function. Conveniently, the controller may be included in acommon enclosure 161 together with the RF source 155 and/or the negativepressure source 115, where the enclosure may be configured to be mountedon a table or a mobile cart, optionally with a fluid source fordelivering a fluid through the sleeve assembly.

In general, as is known in the art, a negative pressure source 115(FIG. 1) is provided for suctioning fluid and cut tissue outwardly fromthe cutting device 102 through an interior passageway 132 in the innersleeve 128. In this variation, the negative pressure source 115 iscoupled to a passageway in the handle 108 as is known in the art, or thenegative pressure source 115 can be coupled to a port 122 on hub 106 ofthe cutting device 102 (see FIG. 1).

Referring to FIGS. 1 and 2, the outer sleeve 125 can be formed from oneor more materials, such as stainless steel, ceramic, plastic or acombination thereof. In one variation, the outer sleeve 125 can besubstantially rigid along its entire longitudinal length. In anothervariation, a sleeve portion proximal to window 140 can be flexible orarticulated while an intermediate portion can be substantially rigid.The outer sleeve 125 can have a substantially uniform diameter as in theillustrated in FIG. 1. In another variation, a diameter of an outersleeve 125 can decrease in the distal direction such that a distalworking end of the outer sleeve 125 has a smaller diameter than aproximal portion thereof.

In one variation shown in FIGS. 2 and 3B, the outer sleeve 125 has ametal extending portion or sleeve 138. An outer ceramic body 142 iscoupled, usually fixedly attached, to a distal end of the metal sleeve138 and has a window or opening 140 therein. The window or opening 140can be formed in a sidewall 141 of the outer ceramic body 142, or thewindow 140 can be partly in the sidewall 141 and partly in a roundeddistal end 143 of outer ceramic body 142 as is known in tubulararthroscopic cutters. In another variation, the window or opening 444can comprise an open end of a working end 400B of an outer sleeve.

As can be seen in FIG. 3A, the inner sleeve 128 has an inner sleevewindow 144 which may be elongated axially and may have a first cuttingside 145 that comprises a first sharp cutting edge 146 and a second RFcutting side 148 that includes an electrode 150. FIG. 1 further showsthat the cutting device 102 may be coupled to a radiofrequency (RF)source 155 and a controller 160 which are operatively connected to theelectrode 150.

As can be understood from FIG. 3A, each of the first and second cuttingsides 145 and 148 of inner sleeve window 144 are adapted for adifferential means of cutting, depending on the direction of rotation ofthe sleeve 128 and thus which cutting side, 145 or 148, is the “leadingedge” for interfacing with, or contacting, tissue when rotating. Thesharp edge 146 is adapted for mechanically cutting tissue or bone whenrotated at suitable speeds. The second cutting edge 148 of window 44 ininner sleeve 128 includes electrode 150 that is adapted forelectrosurgically ablating or cutting tissue.

Referring to FIG. 2, the openings 140 and 144 in the outer and innersleeves, respectively, are configured to receive tissue such thatrotation of inner sleeve 128 relative to the outer sleeve 125 can cut,resect, reshape or modify tissue. In particular, the opening 144 in theinner sleeve 128 extends through an inner sleeve wall 129 and thus is incommunication with the interior passageway 132 (FIG. 1) such that anycut or resected soft or hard tissue can be suctioned through theinterior passageway 132 to a collection reservoir 162.

In the embodiment of FIGS. 2 and 3A, the outer sleeve 125 has a window140 that extends approximately half-way (180°) around the outer ceramicbody 142. The inner cutting sleeve 128 has an inner ceramic body 175 ata distal end thereof, and the inner ceramic body has a window 144 with asubstantially oval or tear-drop shape and a length L in aproximal-distal direction that is greater than its width. It should beappreciated that the window 144 can have other shapes, such asrectangular, circular, square, trapezoidal, etc. By way of non-limitingexample, the length L of the openings 140 and 144 in the outer and innerceramic bodies, respectively, can be in a range of about 2 to 20 mm, forexample, about 4 to 10 mm, depending on the diameter of the working end.

In the variation illustrated in FIG. 3A, the first sharp cutting edge146 is formed on one side 145 of window 144 in the inner sleeve 128 andcan be a straight edge, a serrated edge, a fluted edge, an abrasive edgeor any suitable edge adapted for mechanically cutting tissue or bone.The first sharp cutting edge 146 extends generally in a proximal-distaldirection alongside 145 of window 144 and comprises a leading edge whenthe inner sleeve 128 rotates in direction A indicated in FIGS. 2 and 3A.

FIG. 3A further illustrates the second RF cutting edge 148 of innersleeve window 144 in inner sleeve 128 which includes electrode 150. Theelectrode 150 comprises a suitable material electrode material, such asstainless steel or tungsten, and can be pre-formed to be coupled to theedge 148 of the window or near the edge of the window. The edge 148 andelectrode 150 extend generally in a proximal-distal direction along theside of opening 144 and comprise a leading edge when the inner sleeve128 rotates in direction B indicated in FIGS. 2 and 3A. Referring toFIG. 3A, the inner sleeve 128 can be formed from one or more materials,such as stainless steel, ceramic, plastic or a combination thereof. Inthe variation of FIG. 3A, the inner sleeve 128 has a stainless steelshaft portion 172 that is coupled to a distal ceramic body 175 of awear-resistant ceramic material further described below that isconfigured with window 144. FIGS. 3A and 4A further shows anelectrically insulating and lubricious polymer sleeve 178 covering themetal shaft portion 172 of inner sleeve 128.

Now referring to FIGS. 3A, 3B and 4B, the ceramic body 142 and ceramicbody 175 comprise a monolith that is fabricated entirely of a technicalceramic material that has a very high hardness rating and a highfracture toughness rating, where “hardness” is measured on a Vickersscale and “fracture toughness” is measured in MPam^(1/2). Fracturetoughness refers to a property which describes the ability of a materialcontaining a flaw or crack to resist further fracture and expresses amaterial's resistance to brittle fracture. The occurrence of flaws isnot completely avoidable in the fabrication and processing of anycomponents. The authors evaluated technical ceramic materials and testedprototypes to determine which types of ceramics are best suited for theceramic body 175 with cutting edge 146 as disclosed in co-pending U.S.patent application Ser. No. 14/960,084, filed Dec. 4, 2015, which isincorporated herein by this reference.

In general, the technical ceramics disclosed herein have a hardnessranging from approximately 10 GPa to 15 GPa, which is five to six timesgreater than stainless steel. Such ceramics are 10 to 15 times harderthan cortical bone. As a result, the sharp cutting edges of a ceramicremain sharp and will not become dull when cutting bone, compared tostainless steel. The fracture toughness of suitable ceramics ranges fromabout 5 MPam^(1/2) to 13 MPam^(1/2) which is sufficient to prevent anyfracturing or chipping of the ceramic cutting edges. The authorsdetermined that a hardness-to-fracture toughness ratio(“hardness-toughness ratio”) is a useful term for characterizing ceramicmaterials that are suitable for the invention as can be understood formthe TABLE A below, which compares the hardness and fracture toughnessvalues of cortical bone and a 304 stainless steel with nine exemplarytechnical ceramic materials which are suitable for use in the presentinvention.

TABLE A Ratio Fracture Hardness Hardness Toughness to Fracture (GPa)(MPam^(1/2)) Toughness Cortical bone 0.8 12 0.07:1 Stainless steel 3042.1 228 0.01:1 Yttria-stabilized zirconia (YTZP) 12.5 10 1.25:1 YTZP2000 (Superior Technical Ceramics) YTZP 4000 12.5 10 1.25:1 (SuperiorTechnical Ceramics) YTZP (CoorsTek) 13.0 13 1.00:1 Magnesia stabilizedzirconia 12.0 11 1.09:1 (MSZ) Dura-Z ® (Superior Technical Ceramics) MSZ200 (CoorsTek) 11.7 12 0.98:1 Zirconia toughened alumina 14.0 5 2.80:1(ZTA) YTA-14 (Superior Technical Ceramics) ZTA (CoorsTek) 14.8 6 2.47:1Ceria stabilized zirconia 11.7 12 0.98:1 CSZ (Superior TechnicalCeramics) Silicon Nitride 15.0 6 2.50:1 SiN (Superior TechnicalCeramics)

As can be seen in TABLE A, the hardness-toughness ratio for the listedceramic materials ranges from 98-fold to 250-fold greater than thehardness-toughness ratio for stainless steel 304. In one aspect of theinvention, a ceramic cutter for cutting hard tissue is provided that hasa hardness-toughness ratio of at least 0.5:1, preferably at least 0.8:1,and more preferably at least 1:1.

In some embodiments, the outer and inner ceramic bodies 142 and 175 maycomprise a form of zirconia of a type that has been used as dentalimplants. The technical details of such zirconia-based ceramics can befound in Volpato, et al., “Application of Zirconia in Dentistry:Biological, Mechanical and Optical Considerations”, Chapter 17 inAdvances in Ceramics—Electric and Magnetic Ceramics, Bioceramics,Ceramics and Environment (2011), the full disclosure of which isincorporated herein by reference. Such ceramics may be doped withstabilizers to increase the strength and fracture toughness for use inthe present invention.

In a specific embodiment, the ceramic bodies 142 and/or 175 may befabricated from an yttria-stabilized zirconia commercially availablefrom CoorsTek Inc., 16000 Table Mountain Pkwy., Golden, Colo. 80403 orSuperior Technical Ceramics Corp., 600 Industrial Park Rd., St. AlbansCity, Vt. 05478. Other suitable technical ceramics includemagnesia-stabilized zirconia, ceria-stabilized zirconia, zirconiatoughened alumina, and silicon nitride. In general, in one aspect of theinvention, the ceramic bodies 142 and/or 175 may comprise monolithic ormonoblock ceramic bodies having a hardness rating of at least 8 GPa(kg/mm²). In another aspect of the invention, the ceramic bodies 142and/or 175 may comprise monolithic or monoblock ceramic bodies having afracture toughness of at least 4 MPam^(1/2).

The ceramic bodies 142 and 175 may be fabricated by molding a ceramicpowder, sintering and then heating the molded part at high temperaturesover precise time intervals to transform the compressed ceramic powderinto a ceramic monoblock in the target hardness range and fracturetoughness range as described above. In one variation, the molded ceramicmember part can be strengthened by isostatic pressing of the part.Following the ceramic fabrication process, a subsequent grinding processoptionally may be used to sharpen and/or serrate the sharp cutting edge146 of the inner ceramic body 175. Techniques for fabricating componentscomprising such monolithic or monoblock ceramics are known, but have notbelieved to have been previously been used in the field of arthroscopicor endoscopic electrosurgical cutting or resecting devices.

As can be seen in FIG. 4A, the electrode 150 has a shaft portion 182that extends through the interior passageway 132 in sleeve 128 and hasan electrically insulating coating 180 extending over the electrode'sshaft portion 182 to prevent its contact with metal sleeve portion 172(see FIGS. 3A and 4A).

FIGS. 4A-4B further illustrate an attachment pin 188 in the form of aprojecting element on electrode 150. At least one such pin 188 isadapted to insert into a cooperating recess or bore 190 in the second RFcutting side 148 of window 144 in the inner ceramic body 175. The pinelement(s) 188 can be press fit or fixed with an adhesive in the bores190 to secure the electrode in place in the edge 148 of the window 144.

In the variation of FIGS. 2, 3A-3B, the electrode 150 can comprise anactive electrode as known in the art for use in a submerged arthroscopicprocedure and all or a portion of an outer surface 191 of the metalsleeve portion 138 of outer sleeve 125 can provide a return ordispersive electrode for connection to the RF source 155 (FIG. 1).

In general, a method for treating tissue in accordance with theprinciples of the present invention comprises introducing a working endof an elongated shaver assembly, such as the shaver assembly 102, into atissue surface or other interface, rotating the inner sleeve 128 in afirst rotational direction to cut tissue (soft tissue and bone) with thesharp edge 146 thereof and alternatively rotating the inner sleeve 128in a second opposing rotational direction to cut tissue with theelectrode 150 while delivering RF energy in the form of a cutting orablation current to the electrode. Mechanical cutting with the sharpcutting edge 146 can be particularly effective or otherwise preferredfor cutting hard tissue, such as bone, while RF cutting with theelectrode can be particularly suitable or otherwise preferred forcutting soft tissue.

In certain embodiments, the tissue interface may be submerged in aliquid, for example saline. In other embodiments, saline or otherliquids may be delivered through the shaver assembly to the tissuesurface to flood the target resection region.

The method typically uses a motor (usually incorporated into the shaverassembly or handle) to rotate the inner sleeve 128 in the first andsecond rotational directions at various selected speeds ranging from 100rpm to 50,000 rpm. In one variation, when the sharp ceramic cutting edge146 is used to cut soft tissue, the speed range would be from 100 rpm to10,000 rpm. When the sharp ceramic cutting edge 146 is used to cut bone,the speed range would be higher, for example, from 1,000 rpm to 25,000rpm. When the edge 148 with electrode 150 is used to cut tissue, thespeed range would be, for example, from 100 rpm to 10,000 rpm.

In general, the methods of the present invention may further includesapplying negative pressure from source 115 to passageway 132 in theinner sleeve 128 to extract fluid and cut tissue.

Referring to FIG. 1, the controller 160 is configured to energize theelectrode 150. For example, the controller may energize the electrodecontinuously while the inner sleeve 128 is being rotated continuously inthe cutting direction of arrow B in FIG. 2. In an alternate example, thecontroller may energize the electrode 150 only during a selected arc ofrotation, for example, when the electrode 150 is exposed in window 140while the inner sleeve 128 is being rotated continuously in the cuttingdirection of arrow B in FIG. 2. In still further examples, the innersleeve 128 may be rotationally oscillated so that the electrodealternates travel between the directions of arrows A and B in FIG. 2, inwhich case the controller may continuously energize the electrode or mayenergize the electrode only while travelling in the direction of arrowB.

In another variation, the system can provide a fluid flow from a fluidsource through an inflow pathway (not shown) in the shaver assembly 102to the working end, for example the annular space between the outer andinner sleeves 125 and 128.

In another variation, the controller 160 may be configured to stoprotation of the inner sleeve 128 and the ceramic body 175 in a selectedrotational position relative to the outer sleeve 125. In a selectedstationary position, the electrode 150 can be energized with a form ofcoagulation current for contact coagulation of tissue by the user. Thewindows or openings 140 and 144 of the outer and inner sleeves 125 and128, respectively, can be in or out of alignment in the selectedrotational position to expose the electrode 150 for such contactcoagulation. In another variation, the controller 160 again may beconfigured to stop rotation of inner sleeve 128 and the ceramic body 175in a selected rotational position relative to outer sleeve 125 and thestationary electrode 150 can be energized with a form of cutting orablation current for ablation or contouring of a targeted tissue.Control mechanisms for stopping rotation of the inner sleeve in aselected position may include Hall sensors and microswitches formonitoring rotational speed together with an algorithm for determiningthe inner sleeve's arc of rotation following stopping current to themotor drive.

FIGS. 5A and 5B illustrate distal working ends 400A and 400B of innerand outer sleeves 418 and 415 of an alternate embodiment of anarthroscopic shaver blade or assembly constructed in accordance with theprinciples of the present invention. The distal end 400A of inner sleeve418 is shown in FIG. 5A, and the distal end 400B of outer sleeve 415 isshown in FIG. 5B. As with prior embodiments, the working end 400A of theinner sleeve comprises a distal portion of a metal sleeve 448 fixedlyattached or otherwise coupled to a proximal end of a ceramic body orcutting member 425.

Referring to FIG. 5B, the working end 440B of outer sleeve 415 comprisesa distal body or housing 440 coupled (usually fixedly attached) to adistal end of an elongate proximal metal sleeve 432. The housing 440 canbe a plastic, metal or ceramic, and in an exemplary embodiment comprisesa metal or ceramic material. The ceramic body or cutting member 425 ofthe inner sleeve 418 is rotatably disposed in a window or opening 444 ofthe distal housing 440. The window or opening 444 in housing 440 canextend more than half-way (>180°) around the distal end of the ceramichousing 440 and can thus be larger (have a greater exposed area) thanwindow 140 in the outer ceramic body 142 of FIGS. 2 and 3B.

As can be understood from FIGS. 5A-5B, the metal sleeve 448 of workingend 400A is rotatably received in a lumen or passageway of the metalsleeve 432 of the working end 400B so that the ceramic body 425 orcutting head can rotate and/or oscillate within the window 444 of thehousing 440. The ceramic material of the cutting head 425 is a wearresistant ceramic as described previously.

In a particular embodiment, a wall 442 of distal housing 440 and anouter periphery of cutting member 425 are dimensioned to have a veryclose tolerance so that the rotation of the cutting member 425 withinthe window 444 of housing 440 will shear tissue (i.e., have ascissor-like cutting effect) received in window 450 of the ceramic bodyand windows 444 of the outer sleeve 415 when aligned during rotation (orrotational oscillation) of the cutting member 425 relative to window 444as indicated by arrow A′ in FIG. 5A.

As can be seen in FIG. 5A, the opening or window 450 of ceramic cuttingmember 425 can extend over a radial angle of from about 20° to 90° ofthe periphery. In this variation, the window 450 is closed to provide arounded distal nose 456 of the ceramic cutting member 425. In anothervariation (not illustrated), the window 450 can be open around thedistal nose of the cutting member 425 (thus resembling the open distalend of the housing 440 of the working end 400B). The length of window450 can range from 2 mm to 10 mm depending on the diameter and design ofthe working end 400A.

FIG. 5A further shows that the ceramic cutting member 425 has a firstedge 455 that is sharp on one side of window 450 similar to theembodiment of FIGS. 3A and 4B. In addition, the ceramic cutting member425 is configured with a plurality of sharp burr edges 460 which canextend helically, axially, longitudinally or in a cross-hatchedconfiguration around the exterior surface of the cutting member 425, orany combination thereof. The burr edges 460 and the sharp edge 455 ofwindow 450 are adapted to resect soft tissue when rotated or oscillatedin an interface with soft tissue wherein the cutting member edges movein scissor-like contact with the lateral side portions 462 of outersleeve housing 440 as can be understood from FIGS. 5A and 5B. In thisvariation, the burr edges 460 and sharp window edge 455 also are adaptedfor cutting bone at high rotational speeds.

Still referring to FIG. 5A, the cutting member 425 may have a secondedge 465 around one side of window 450 that carries electrode 470 forelectrosurgically cutting soft tissue. In this variation, the electrode470 may comprise a conductive wire, such as tungsten, that has a shaftportion 472 that extends through a through-hole or bore 475 in theceramic cutter 425 in proximal body portion 476 of the cutter. Theelectrode 470 has a distal end 480 that is inserted into another bore482 in the ceramic cutter 425. The distal end 480 of electrode 470 canbe press fit in bore 482 or bonded in said bore.

In another variation, as shown in FIG. 6, a distal end 480′ of electrode470 can extend through a bore 482′ in the ceramic body 440, and a weld488 or crimp can be used to secure the distal end 480′ in bore 482′.Referring back to FIG. 5A, the proximal shaft portion 472 of electrode460 can be covered with an electrically insulating sleeve, as describedpreviously. and extend through the lumen 490 in inner sleeve 418.

Although particular embodiments of the present invention have beendescribed above in detail, it will be understood that this descriptionis merely for purposes of illustration and the above description of theinvention is not exhaustive. Specific features of the invention areshown in some drawings and not in others, and this is for convenienceonly and any feature may be combined with another in accordance with theinvention. A number of variations and alternatives will be apparent toone having ordinary skills in the art. Such alternatives and variationsare intended to be included within the scope of the claims. Particularfeatures that are presented in dependent claims can be combined and fallwithin the scope of the invention. The invention also encompassesembodiments as if dependent claims were alternatively written in amultiple dependent claim format with reference to other independentclaims.

1. A surgical system comprising: an outer sleeve having a longitudinalaxis and an opening in a distal region thereof; an inner sleeverotationally disposed within said outer sleeve, said inner sleeve havinga distal region, a proximal region, and an interior passageway disposedtherebetween, wherein a cutting window is formed in a wall of the distalregion of the inner sleeve; a cutting edge on one side of the cuttingwindow; and an electrode on an opposite side of the cutting window;wherein rotating the inner sleeve in a first rotational directionrelative to the outer sleeve cuts tissue with the cutting edge androtating the inner sleeve in a second rotational direction opposite tothe first rotational direction cuts tissue with the electrode.
 2. Thesurgical system of claim 1 further comprising: a motor configured toselectively rotate in the inner sleeve in first and second rotationaldirections; and a radiofrequency (RF) current source configured to becoupled to the electrode
 3. The surgical system of claim 2 furthercomprising a controller operatively coupled to the motor and to the RFsource.
 4. The surgical system of claim 3 wherein the controller isconfigured to selectively operate in a first mode in which the motorrotates the inner sleeve in the first rotational direction with theelectrode not energized and in a second mode in which the motor rotatesthe inner sleeve in the second rotational direction with the RF sourcedelivering a cutting current to the electrode to cut tissue.
 5. Thesurgical system of claim 4 wherein the controller is further configuredto selectively operate in a third mode in which the motor drive isstopped with the RF source delivering a cauterizing current to theelectrode to coagulate to tissue.
 6. The surgical system of claim 4wherein the controller is further configured to selectively operate in afourth mode in which the motor drive is stopped with the RF sourcedelivering a cutting current to the electrode to cut or ablate tissue.7. The surgical system of claim 4 wherein the controller is configuredto selectively operate in a fifth mode in which the motor rotationallyoscillates the inner sleeve relative to the outer sleeve in the firstand second rotational directions.
 8. The surgical system of claim 2further comprising a hub at a proximal end of the shaft assembly,wherein the hub is detachably connected to the motor.
 9. The surgicalsystem of claim 1 wherein a proximal portion of the shaft assembly isconfigured to be connected to an external fluid source to deliver afluid through a passageway in the shaft assembly and release the fluidfrom a distal region of the shaft assembly to a tissue interface. 10.The surgical system of claim 1 wherein a proximal portion of the shaftassembly is configured to be connected to an external vacuum source todraw a vacuum through a passageway in the shaft assembly to aspiratefluid from a tissue interface at a distal region of the shaft assembly.11. The surgical system of claim 1 wherein at least the cutting edge ofthe inner sleeve comprises a ceramic.
 12. The surgical system of claim11 wherein the entire distal portion of the inner sleeve comprises theceramic.
 13. The surgical system of claim 3 wherein the controller isconfigured to stop rotation of the inner sleeve in a selected rotationalposition relative to the outer sleeve.
 14. The surgical system of claim13 wherein the opening in the outer sleeve and the window in the innersleeve are rotationally aligned in the stopped position.
 15. Thesurgical system of claim 13 wherein the opening in the outer sleeve andthe window in the inner sleeve are out of rotational alignment in thestopped position.